Interpretive Summary: Research addresses the hypothesis that grazing intensity during and following drought can dramatically alter community level, post-drought recovery patterns and that current drought and/or post-drought livestock grazing intensities tend to suppress recovery rates. Research was conducted during the 1993 through 1996 growing seasons at the Fort Keogh Livestock and Range Research Laboratory located near Miles City, Mont. Study plots were twelve 5 X 10-m non-weighing lysimeters constructed in 1992 on a gently sloping (4%) clayey range site. An automated rainout shelter was constructed to control the amount of precipitation received on 6 lysimeters during the 1992 growing season. We conclude from study results that the independent and combined effects of the imposed drought and grazing treatments were minimal relative to soil water dynamics and aboveground net primary production although both grazing treatments reduced herbage standing crops. Although study results provide minimal support for our original hypotheses, we believe it unwise to summarily reject the hypothesis for 2 reasons. First, the imposed drought was most likely initiated too late in the growing season to dramatically reduce current year herbage production. The second reason the effects of the drought may have been dampened was because the amount of ambient precipitation received on the non-drought plots during the imposed drought was well below normal. Thus, late growing season production in the non-drought, control plots may have been curtailed also.

Technical Abstract:
Research addresses the hypothesis that grazing intensity during and following drought can dramatically alter community level, post-drought recovery patterns and that current drought and/or post-drought livestock grazing intensities tend to suppress recovery rates. Research was conducted during the 1993 through 1996 growing seasons at the Fort Keogh Livestock and Range Research Laboratory located near Miles City, Mont. Study plots were twelve 5 X 10-m non-weighing lysimeters constructed in 1992 on a gently sloping (4%) clayey range site. An automated rainout shelter was constructed to control the amount of precipitation received on 6 lysimeters during the 1992 growing season. We conclude from study results that the independent and combined effects of the imposed drought and grazing treatments were minimal relative to soil water dynamics and aboveground net primary production although both grazing treatments reduced herbage standing crops. Although study results provide minimal support for our original hypotheses, we believe it unwise to summarily reject the hypothesis for 2 reasons. First, the imposed drought was most likely initiated too late in the growing season to dramatically reduce current year herbage production. The second reason the effects of the drought may have been dampened was because the amount of ambient precipitation received on the non-drought plots during the imposed drought was well below normal. Thus, late growing season production in the non-drought, control plots may have been curtailed also.